Modified auxiliary boundary conditions method for an ill-posed problem for the homogeneous biharmonic equation

In this paper, we are interested in the inverse problem for the biharmonic equation posed on a rectangle, which is of great importance in many areas of industry and engineering. We show that the problem under consideration is ill-posed; therefore, to solve it, we opted for a regularization method via modified auxiliary boundary conditions. The numerical implementation is based on the application of the semidiscrete finite difference method for a sequence of well-posed direct problems depending on a small parameter of regularization. Numerical results are performed for a rectangle domain showing the effectiveness of the proposed method.     

SPE for the simultaneous determination of various isothiocyanates

Several SPE sorbents were investigated for the extraction of a group of chemically diverse isothiocyanates (ITCs). They included bonded silica, carbon‐based, and polymer‐based sorbents with various functional groups. Results showed large differences in the ability of these sorbents to simultaneously extract ITCs from standard solutions. Recovery rates were on average the highest with divinylbenzene (DVB) based polymeric sorbents, especially with a DVB/N‐vinylpyrrolidone copolymer that had recovery rates ranging between 86.7 and 95.6%. These sorbents achieved the most balanced extraction efficiency between aliphatic and aromatic, polar, and nonpolar ITCs. With graphitized carbon, C₁₈‐bonded silica, and amide‐containing sorbent, recovery levels were higher for the two least polar aromatic ITCs (benzyl ITC and phenylethyl ITC), whereas for the polar aliphatic ITCs levels were the lowest. The least retained one, was methyl ITC that is the most polar with recoveries between 0 and 31.5%. The presence of amide groups, especially in a polyamide sorbent, appeared to be particularly unsuitable for the extraction of aliphatic ITCs. A copolymer made up of DVB and N‐vinylpyrrolidone was therefore shown to be the most suited for the extraction of both aliphatic and aromatic ITCs.     

Impedance studies of Sb doped SnO2 thin film prepared by sol gel process

Antimony-doped tin oxide thin films have a range of technological applications as conductive coatings, and sol-gel processing seems to offer some advantages over other coating techniques. In this study antimony-doped tin oxide (ATO) thin films have been prepared by the sol-gel dip-coating (SGDC) process, using tin (II) chloride dehydrate (SnCl₂, 2H₂O) and antimony (III) chloride (SbCl₃) as host and dopant precursors respectively. The structure of the (ATO) powders was analysed by X-ray diffraction (XRD) and the microstructure of the thin films by atomic force microscopy (AFM). These investigations show that the structure is tetragonal rutile type and that an increase in Sb-doping decreases the crystallite size of the (ATO) particles. To analyze the impedance spectroscopy data, the Nyquist (Z″ vs. Z′) plots as well as the representation of imaginary (Z″) and real (Z′) parts of impedance vs. frequency were used. The Nyquist plots suggest that only the grain boundaries are responsible in the conduction mechanism of the material. From the variation of lnσ vs. inverse of absolute T we have deduced the activation energy found to be 0.87 eV.     

Polymers for electrochemical devices

Polymeric materials are already present in electrochemical storage devices such as batteries and PEM fuel cells. The polymer is an electro-active material in lithium polymer batteries. Several network based polymer electrolytes provide thermal, mechanical and redox stabilities, while insuring a high conductivity level. Linear unsaturated polyether precursors may be obtained either by step-growth polymerization from oligomeric polyethers, or by ring-opening polymerization from oxirane mixtures. Some prototype performances, performed on a 10 Wh lithium polymer cell, are presented and discussed.